We’re rewarding the question askers & reputations are being recalculated! Read more.

# Questions tagged [proportional-hazards]

Proportional hazards is an assumption of the Cox proportional hazards model of survival analysis and some other models as well. The assumption is that a linear increase in the predictor will have a uniform multiplicative relationship with the hazard.

12 questions
Filter by
Sorted by
Tagged with
1k views

### Expected survival time for Weibull proportional hazards model with R's predict.survreg

The predictions for a Weibull proportional hazards model from R's predict.survreg() are not the expected survival times. Please help me understand this behaviour. ...
640 views

### Violation of the proportional hazard assumption, interaction with time. Am I taking the correct steps?

I will try to keep my question as short as possible. For my thesis I am researching if a risk score can predict graft failure in a cohort of $596$ patients over the course of $10$ years. (The ...
2k views

### Proportional hazards assumption and time-dependent covariates

Is there a way to check that the proportional hazards assumption is correct for a Cox model with time-varying covariates ?
129 views

### Hazard ratio for more than two groups

Consider the line of code below for implementing Cox model in R and finding the hazard ratio: fitcox <- coxph(Surv(Survival,Death) ~ clusters, data = data) ...
427 views

### Cox proportional model with multiple failures for same subjects

I have a dataset that I'm trying to model using Cox proportional hazard models. The data include patient IDs and several attributes about the patients (including time till failure). Due to the nature ...
4k views

### Determine if a time-dependent Cox model is appropriate

Before the description, here are my questions (1) Is the set-up of my time-dependent data correct? (2) Are the ways I run my Cox proportional hazard model with a time-dependent variable/ non time-...
655 views

### Does the proportional hazards assumption still matter if the covariate is time-dependent?

If I estimate a Cox Proportional Hazards model and my covariate of interest is dependent (continuous or categorical), does the proportional hazards assumption still matter? I recently went to a ...
3k views

### Can a Cox proportional hazards model be used on general left-censored data (i.e. non-survival data)?

A familiar problem in applied science is having censored data, in particular left-censored data arising due to an assay or piece of equipment having a lower limit of detection (LOD). Assuming a ...
959 views

### How to manually calculate survfit in cox hazard model?

Here is a toy survival model with age only. But I still do not know how the surv numbers in survfit are calculated: \$\exp(\beta ...
271 views

### Schoenfled Residua test shows proportionality hazard assumptions holds but Kaplan-Meier plots intersect

"If Kaplan-Meier plots cross each other then proportional hazard assumption does not hold". The issue I am facing is that I got the Kaplam-Meier plot(bleow). We can clearly see that it is overlapping. ...